Ducting for clothes dryers carries hot air from the dryer out of the building, and must do so safely and efficiently. Typical problems encountered with ducting is that the external air vent and the dryer are variable distances from one another, so the ducting must be able to accommodate varying configurations. Also, the ducting must be heat resistant, so that the hot dryer air does not melt the ducting, as well as any stray lint caught within the ducting does not cause a fire. The ducting must be of a low profile so that it fits behind the dryer, and rigid enough that it cannot be crushed by the dryer being pushed against the wall or during operation of the dryer.
One attempt at addressing these needs is U.S. Pat. No. 5,645,482, (Moss), which provides a rigid telescopically-extensible air duct connector made from sheet metal, one end of which fits within the dryer's duct port, and the other end of which attaches to the external air vent. This air duct connector is somewhat heat proof as a result of being made of metal, and narrow so that it fits behind the dryer, but it is limited in the range of connections that can be made. For instance, the extension cannot reduce to a smaller length than that of one of the telescopic sections, and it only works where axes of the dryer vent and the exterior vent are parallel.
Another attempt at a system for venting dryers is U.S. Pat. No. 6,230,418, which permits installation of a metal venting system assembled from low-profile ducts. Again, the same limitations as Moss are present here: the vent is limited in the range of connections that can be made, and only works where the axes of the dryer vent and the exterior vent are parallel.
Recently, flexible aluminum foil formed into a tube, with a shape that is held by coiled wire, has become the de facto standard for adapting a dryer vent to the exhaust vent. However, this foil duct is not rigid and is therefore prone to being crushed by the dryer when it is pushed against a wall or during operation of the dryer. If the vent is crushed or otherwise does not provide an easy path for the air, it may create backpressure reducing dryer efficiency or worse, may trap lint and risk causing a fire. Accordingly, there is a need for a device that holds the duct from being crushed while permitting the foil duct to extend unimpeded between the dryer vent and external vent.